Remove transformers versions with Kimi tokenizer regression

[derek-tml]

Summary

Exclude Transformers releases that force Kimi K2.5/K2.6 through TokenizersBackend, while allowing 5.5.4 where the upstream forced-backend entry for kimi_k25 is removed.

Details

A version audit over the relevant released range found:

• 4.57.6, 5.0.0, 5.1.0, 5.2.0: no MODELS_WITH_INCORRECT_HUB_TOKENIZER_CLASS forced-backend table
• 5.3.0: forced-backend table exists, but does not include kimi_k25
• 5.4.0, 5.5.0, 5.5.1, 5.5.2, 5.5.3: table includes kimi_k25, causing AutoTokenizer to ignore Kimi tokenization_kimi.TikTokenTokenizer auto-map
• 5.5.4: released on PyPI and no longer includes kimi_k25 in the forced-backend table

This changes the dependency bound to transformers>=4.57.6,!=5.4.*,!=5.5.0,!=5.5.1,!=5.5.2,!=5.5.3,<=5.5.4.

Validation

• git diff --check
• parsed pyproject.toml with tomllib and confirmed the dependency spec